Torsional vibration damper



April 11, 1944. R, M, HElNTZ 2,346,432

TORS IONAL VIBRATION DAMPER Filed Nov. 1o, 194:2

Puentes Apr. 11, 1944 .UNrrEo STATES PATENT! OFFICE 'ronsloNAL :',llou mman I Ralph M. Heints, Cleveland, Ohio, assignor to Jack .t Beints, Incl, Bedford, Ohio, a

tion of Ohio corpora- Appuemen November/10,1942, serai No. 465,110 f z clelia. (c1. 64-1) This invention relates to, a torsional vibration damper for rotating machines and the like.

e Machines and accessory devices driven from a pulsating power .source such as an internal combustion engine are subjected to torsional stresses l far in excess of the calculated load stress arising from the delivery of useful power, because of pvariations in angular velocity resulting from an uneven flow of power. An object of the present invention ls to provide a/driv'ing arrangement which will prevent the transmission of vibratory torsional stresses to a machine or apparatus-being driven, and a particular object is to provide an improved torsional vibration damperior ro tatins bodies.

A further object is to provide means for ab sorbing and dissipating increments oi torsional` vibration energy input to prevent' the building up of torsional vibration in a rotating body.

The principles oi the invention are illustrated in connection with an aircraft generator adapted to be driven by an aircraft power plant. v

The ngure in the drawing is an elevational view of an aircraft generator amature with parts broken away to reveal the construction of the vibration damper in section.

The numerals i and 2 designate bearing supports for armature bearings 3 and d in the generator housing, the field structure being omitted as immaterial to the invention. The armature comprises the usual laminated and slotted core b,

yand oommutator 8. A drive shaft 'l has a splined driving end l, a neck 9, a splined portion iii, an elongated and reduced quill ii, and a taperedend. portion `i2 having key ways for keys i3, and a threaded tip il. A stiff tube i5 surrounds lthe shaft 1 and is keyed`by said keys to the tapered end I2, the tube and shaft being held together in the relationship shown by means of a nut IB, and the combination being carried inthe bearing I as shown. ln the present embodiment the core ll and commutator i are mounted on a sleeve *il which may be pressed on the tube I5, but these parts may be carried directly by the tube Il ii desired. A thimble or short sleeve I8 may beeinployed to position and retain the sleeve Il on the tube il. 1 The tube il provided with a hanged end united with a hollow hanged' journalgi bymeans of screws 22, the hollow journal 2l being carried e in the bearing 3,' Froma structural standpoint the hollow journal `2| may be considered as part of the tube I5. A friction plate 23 is mounted for axial movement on the splined. portion Il.

I this plate beingin frictionalengagement with armature the inner surface oi `the flanged journalli and a.

ring 2-4. A plurality of springs 25 are carried by the hanged end 20 to support the ring 24 and urge it against the friction plate 23 which is in tum brought to bear against the said inner surface of the ilang'edv journal 2i. It isnoted that the parts herein described support the s pliued end s of the shaft 1 rather loosely in what might be called a floating support to allow the end t to accommodate itself to some degree to relative misalignmentof the power take off shaft on the engine, or prime mover, after the manner of a universal Joint. It is noted that the neck portion i is spaced within the iournal 2t so as to receive 5 no support or guidance therefrom, lateral movement of the shaft end ii being subject to the restraint imposed by the frictionai engagement the rotational moment oi inertia of the mass of the core 5 and oommutator 5 carried by the relatively stii! tube it, the quill portion ii is designed as a resilient torsional spring to absorb the input energy and` displacement of the forced vibrations. As the inertia oi' the rotating mass resists any change in angular velocity the vibratory accelerations and deeelerations imposed upon 'the driving end s produce torsional deiiectior in the quill ii so that at the end i2 there are no vibratory forces of a magnitude sufficient to materially influence thereby enabled to rotate at a steady speed substantially unaffected by the power impuls oi the prime mover so that the structure as a whole is protected from torsional vibration stresses.

rails into resonance with a natural frequency of torsional vibration of the armature additional means must be provided to prevent n large amplitude resonant vibration of the armature. Under auch conditions the friction plate 23 absorbs and dissipates sumcient energy to prevent the building yupof resonant vibrations, since a phase difierence would tend to'exist between the vibrations 'in shalt end 8 and those in the iiange end 20 of the stiii tube I5. While the frictional drag of the plate 23 is suiiicient to damp out torsional and lateral vibrations, it is not sufficient however to be effective in transmitting forced vibrations directly from the shaft end 8 and plate 2l to the the rotating mass. The mass of the armature is- .'When the frequency of the power impulses- While the principles of the invention have been described in connection with an aircraft generaI tor for purposes of illustration, it is to be disa tinctly understood that they are equally applicable to protect any revolving mass from forced torsional vibrations. The invention is of para ticular advantage in driving accessory devices generally on internal combustion engines, and may also be embodied in motors or other prime movers connected with variable or pulsating loads.

claim: Y

i. In a machine adapted to be rigidly mounted on and driven from a pulsating power source, a rotor rigidly mounted on a stii tube, end bearings for said tube supporting said rotor in said machine, a resilient drive shaft in said tube, one end of said shaft being connected with one end oi said tube and the other end of said shaft extending from the other end of said tube ior external driving connection, a friction plate rigidly secured to said tube adjacent said other end thereof, a friction plate mounted on said shaft so as tc assume the torsional and lateral vibrations there= oi, and means to maintain frictional engagement between said plates to dampen said vibraadsense tions, said extending end of said shaft having tor*` sional and lateral freedom of vibration under the restraint of said damping action. V

2. In a machine adapted to be rigidly mounted d on and driven from a pulsating power source, e. pair of bearings, a sti tube mounted in said bearings, a rotor for said machine built up around said tube, a resilient drive shaft in said tube, one end of said shaft being connected with one end of l@ said tube and the other end of said shaft extending from the other end of said tube for external driving connection, a hollow ange on said tube between said bearings having a friction surface therein, a friction plate within said ange, said l5 plate having a sliding splined connection with said shaft for longitudinal movement thereon and having radial clearance within said ange to allow lateral movements o said shaft within said tube, and spring means associated with said ange 2i? to maintain frictional engagement between said plate and said frictional suriace,'said arrange ment serving to dampen torsional vibration and 'to accommodate misalignment o said rotorA beare ings and said driving connection.v ad H M. Z. 

